The present invention relates primarily to a fluorescent lamp and more particularly to a circular annularly nested fluorescent lamp having a tubular bridged connection with effectively increases the tube length to provide a high lumen output.
Today, there are many styles of fluorescent lamp tubes, some of which are the conventional longitudinal tubes, others in the form of compact U-tubes and still others, circular. To effectively increase the lumen output when used in a typical fluorescent lighting plurality of lamps are used.
In the case of the circular lamp, it can be configured using a plurality of circular lamps, arranged of different diameters so that they are coaxially circular in the same radial plane. This configuration, however, has the disadvantage that when individual lamps are used, the lighting fixture becomes unnecessarily large and more expensive due to the fact that for each individual concentrically nested lamp, there is a pair of electrodes at each end, each pair requiring a ballasting arrangement.
To overcome this disadvantage, a pair of nested concentric lamps, lying in one and the same plane, can be connected using a hollow tubular bridge to increase the effective tube length, where only a single pair of electrodes is used, one at each end, and where only one ballasting arrangement is used.
When two lamps of the same cross sectional diameter are connected by a hollow tubular bridge to effectively increase the lamp discharge path for increased lumen output, with continued operation over time, the innermost annular concentric tube, becomes more difficult to ignite, requiring a higher ignition voltage.
Examples of such prior art are shown in the examples that follow.
U.S. Pat. No. 5,034,655, granted Jul. 23, 1991, to S. Murayama, et al., discloses a fluorescent lamp having a pair of electrodes, at least two circular discharge tubes connected to said electrodes, containing a rare gas and mercury and having a phosphor coating on the inside wall. The tubes are arranged coaxially circular in the same radial plane.
U.S. Pat. No. 2,446,712, granted Aug. 10, 1948, to H. A. Mcllvaine, discloses a fluorescent lamp having double spiral grooves in a glass body, containing a gaseous vapor, the grooves being sealed with a glass cover plate, and having electrodes at the sealed ands of the grooves. The electrodes are configured at each sealed end in two configurations, both inwardly and outwardly.
U.S. Pat. No. 2,309,676, granted Feb. 2, 1943, to G. T. Schmidling, discloses a fluorescent lamp fixture having a circular fluorescent lamp mounted within a bell shaped reflector and housing. Further disclosed is a fluorescent lamp having an improved coating that reproduces the color quality equivalent to the sky-shine plus noon sunlight.
All of the above referenced prior art disclose circular fluorescent lamps, ones that are coaxially circular, or spiraled radially, where all the tubes reside coplanar.
What is needed are concentrically nested, circular fluorescent lamps that are tubularly bridged and can be arranged for use in uplighted torchere styled lighting fixtures as well as table lamps and pendant types of downlighted fixtures, where each concentric lamp of different diameters, lying in different planes, having each plane parallel to each other, either above or below the other; a lamp that can be started at a lower voltage for operation on a nominal 117 AC volts.
It is therefore an object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, each connected to each other using a hollow tubular bridge, to increase the discharge path length, for increased lumen output.
It is another object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, where each concentric lamp of different diameter lying in different planes, each plane being parallel to each other, either above or below the other.
It is still another object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, where the tube diameter for each concentric lamp differs and is adjusted to have an equal volume for the entrapped gas for each concentric ring section.
It is still yet another object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, where the tube diameter for each concentric lamp differs and is adjusted to have an equal volume for the entrapped gas for each concentric ring section that will have a lower starting voltage that is compatible for use in 117 VAC applications.
Yet, it is another object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, where each circular ring does not lie in the same plane, that are arranged for use in an uplighted torchere floor lamp.
Yet still, it is a another object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, where each circular ring does in the same plane, that are arranged for use in a downlighted ceiling mounted lighting fixture.
It is a final object of the present invention to provide for a circular fluorescent lamp, having a plurality of nested concentric tubes, where each circular ring does not lie in the same plane, that are arranged for use in a downlighted table or desk lamp.
These as well as other objects and advantages of the present invention will be better understood and appreciated upon reading the following detailed description of the preferred embodiment when taken in conjunction with the accompanying drawings.
The present invention relates primarily to circular fluorescent lamps, and in general, to a plurality of circular lamps that are concentrically nested to increase the available lumen output. By coupling together two circular fluorescent lamps, an inner and an outer circular fluorescent lamp, using a hollow glass tubular bridge, a dual circular fluorescent lamp having an increased discharge path is created.
If each lamp section, both the inner and outer section have the same cross sectional area by using the same diameter tubing during the manufacturing process, the finished product performance deteriorates over a period of time. With the passage of time over its useful period, the innermost lamp becomes more difficult to ignite, generally requiring an increased ignition voltage and if none is available, the useful life of the lamp ends, thereby necessitating replacement.
To overcome this objectionable performance, the prior art requires that the lamps, both circular as well as spiral, have tubes that reside coplanarly. This requirement is due to the fact that the entrained inert gas and mercury vapor migrate toward the larger diameter circular tube. The volume of the outer larger diameter ring is greater than the inner smaller diameter ring and when the arc is formed within the tubes, the temperature of the gas and vapor increases. According to Boyle""s Law, the pressure is greater in the innermost circular tube than it is in the outermost tube because of the difference in the volumes of the two circular tubes, when operating at a constant temperature. When the lamps are turned off and as the lamps cool, the mercury vapor migrates toward the outer tube having the lower pressure, where it condenses, leaving less vapor in the inner circular tube, making it more difficult to restart.
In the first aspect of the present invention, to keep the pressure gradient across the hollow tubular bridge at zero, the cross sectional diameter of the innermost ring is increased so that the volume of each circular ring is equal, thereby maintaining a constant pressure in both the inner and outer ring.
In a second aspect of the present invention, by increasing the cross sectional diameter of the innermost tube and by allowing it to be in a plane lower than the plane of the outer tube, it becomes ideally suited physically for use in a torchere lamp, as well as many other styles of lighting fixtures and lamps.
Also, by increasing the cross sectional diameter of the innermost tube and by allowing it to be in a plane higher than the plane of the outer tube, it becomes ideally suited physically for use in a downlighted fixture such as a ceiling lamp, table lamp or in a pendant style fixture.